The second episode of performances at the judges' houses came and went without a true standout. So it was up the star power of Justin Bieber and Wil.i.am, guest coaches invited by judges L.A. Reid and Britney Spears respectively, that buoyed the show.

The episode starts off at L.A. Reid's house in Beverly Hills, where he reiterates his distaste for landing the "Over 25" group. He mentions he's better at fostering young talent -- like his guest judge Justin Bieber -- and implies the group must fight to impress him in order to make it to the next rounds.

First up is Jason Brock, and the voice that surprised us in his first tryout is back, lush and strong. In a markedly different reaction than we've become used to in last episode, Brock leaves the stage truly satisfied.

"I felt so good about that," Brock beams. "It went out the way I wanted it to."

The judges agree, but then for some reason express concern about him being "the one"-- a notion that there are several crucial factors beyond a singing voice to consider. It’s a theme revisited throughout the episode that weighs down otherwise solid performances.

Next is David Correy, and his voice is much better than expected--he soars through his song's rising lines and has a particularly expressive tenor. Bieber is impressed. "I saw pure passion," says his manager, Scooter Braun, who gives most of the worthwhile advice from this segment. Reid maintains his skepticism here, appraising the performers' pop-star potential over his musicality.

"Talent isn't a question. Viability in the marketplace is a question," Reid says, clearly referring to Correy's tattoos and strong personality..

Daryl Black is up next, and his performance is a reminder of how perfect he is for R&B vocals. His voice is even and delicate and Reid says "you felt that" when Black's performance is over, another satisfyingly different reaction than last night's candidates had to their own music. Braun likes him, as does Bieber, only less articulately than his manager. Reid does mention thta he "didn't find the voice tone to be unique," which is tough to imagine after such a passionate performance.

Reid likes the song choice by the next performer, Tate Stevens, who sings a countrified version of Brian McKnight's "One," and he sings it confidently, but without some of the usual inflection that permeates his actual country songs.

"There's something about him that you just want to root for," Braun says, continuing to outshine the much better known Reid and Justin Bieber as judges.

Vino Alan performs after getting into his abusive childhood and explaining how “The X Factor” would help give his son the upbringing he was never able to have for himself.

"I felt it. Emotionally, I felt it," Bieber offers, after we see Reid giving his signature head bobs of approval. But he throws ice water on the enthusiasm.

Tara Simon goes next, and sings Hoobastank's “The Reason,” a song I'm barely able to listen to in its entirety even when performed by the original performers. Predictably, Simon's version isn't much better, and she is in the thick of vocal filigrees before she even hits the chorus. She leaves thinking she's done a perfect job, though the judges beg to differ.

"She's got a big voice, but she should make sure to have those more sweet moments with her voice," Bieber stutters, a true statement that falls flat with his delivery and its vague nature. But viewers have already moved on - to Malibu to meet Britney’s group.

Britney Spears announces Will.i.am is her celebrity assistant, because "he has such a fresh sound and he knows what kids are listening to." That just makes Spears seem either odd or old.

Diamond White is up first, a position she must be used to by now, and sings strongly and accurately with no real flaws. Spears agrees somewhat, with one caveat.

"She cares about her moves too much," Spears says. "I think she needs to work on her stage performance."

Next is Reed Deming, the Bieber lookalike. His version of "Hey There Delilah," by the Plain White Tees is solid and mistake-free. Spears thinks he can do better, and Will.i.am, in his first of several confusing comments, mentions, "he's like a little emperor kid."

Afterward, rapper James Tanner performs, and his superior stage presence is clear. However, his uniqueness is not--a melodically flat performance doesn't bring much more to the table than a healthy bit of energy.

"I thought he was very entertaining. I'm just not convinced it was strong enough," Spears says in her most accurate commentary of the night.

Next we see the two judges counseling “X Factor” veteran Arin Ray, who hopes to improve upon his showing last year, when he was on a group at this point.. They offer bland and useless advice: "It's just gotta spill out of you," Wil.i.am says. Spears suggests staying "true to yourself," and also, to "bring the goods."

Ray’s voice is Usher-like and is one of the better performances of the night, clearly a result of Ray's experience with both the show and a year's worth of practice time.

"He definitely has a potential ‘X Factor’ in him," Will.i.am notes.

"He has to work on his vocals a little bit, but I love watching him," Spears adds.

Carly Rose Sonenclar, an early darling of Spears' in the tryouts phase, provides the final performance. Beforehand, the two judges suggest that she add a bit more passion into her technically masterful voice, and her performance shows the advice in action. Her already polished, round voice has some energy behind it, and Will.i.am is so impressed he's given to forced animal metaphors to describe his reaction.

“She's like a little caterpillar, and then you think she's gonna turn into a butterfly," Will.i.am says, pausing for effect. "Dragon. Burnin' up. Scorchin' the town."

"She's a very talented young girl," Spears adds, bringing the criticism back to reality. "I'm just sort of scared that she may not be able to cope with the pressure of everything."

That’s ironic coming from a pop star, who until recently had been famous for her own public meltdowns following the pressure of her superstardom.

Overall the episode was depressingly devoid of meaningful musical advice. One would think years of experience in the music business would give a stronger sense of judgment to Spears, and an almost excessively critical vocabulary to Reid, who makes his living judging performers as a producer when the cameras aren't rolling. But neither impress, and it's clear Lovato's group is the one to watch, both for her excellent advice and the strength of her roster.